Recipe Calculation for Polyester Cotton Blended Fabric Dyeing

Introduction

Polyester/cotton blended fabric dyeing process is complex. Because cotton and polyester are two different fibers that come from natural sources and are synthetically produced consecutively. These two fibers have different physical characteristics, such as length, diameter, strength, elasticity, torsional rigidity, frictional properties, and chemical properties, such as thermal properties, density, resistance to chemical agents.

Cotton is very resistant to alkalis, but aqueous alkalis can seriously damage polyester. Polyester should not be pressure boiled in alkalis, as this speeds up the deteriorating process. Terylene fiber is fully alkali resistant for its purpose as a textile fiber. The alkali sensitivity of polyester/cotton blends should be considered when scouring them. The polyester/cotton blends with more cotton require more scouring and bleaching agents in pretreatment because cotton fibers hold more dirt and impurities than polyester fibers. The purpose of this article is to explain how to calculate dyeing recipes for polyester and cotton blend fabric.

In this case, we will be using a two-stage method using a single bath. We generally use this method for dyeing knits and yarns for dyeing machines such as winches, jets, beams, or package dyeing machines. According to this method, the polyester part of the material is dyed first with disperse dyes, after which the cotton part of the material is dyed with reactive dyes.

Typical recipe for polyester part

Chemical name	Recipe amount
Dispersing agent	1 gm/L (Stock Solution 1%)
Sequestering agent	2 gm/L (Stock Solution 1%)
Levelling agent	2 gm/L (Stock Solution 1%)
Carrier	3 gm/L (Stock Solution 1%)
Acetic acid	2 gm/L ( to maintain pH=4-5)
Disperse dyes(Yellow)	2% (Stock Solution 1%)
Temperature	130-1350 C
Time	30-60 mins
M:L	1:20
Sample weight	5 gm

Typical recipe for cotton part

Chemical name	Recipe amount
Wetting agent	1 gm/L (Stock Solution 1%)
Levelling agent	1 gm/L (Stock Solution 1%)
Common salt	70 gm/L
Soda ash	4 gm/L (Stock Solution 1%)
Reactive dye(Yellow)	2% (Stock Solution 1%)
Temperature	50-600 C
Time	30-50 min
pH	10.5±0.5
M:L	1:20

Blended Fabric Dyeing Procedure:

Dyeing Curve 01: Polyester/cotton blend fabric dyeing curve

1.   A dyebath with substrate should be set at 50°C temperature, then the dispersing agent, acetic acid (pH around 4-5), as well as other auxiliaries should be added, and then the dyebath should be run for 5-10 minutes.
2. A dye solution of disperse dyes should be added and the temperature should be raised to 70-80°C.
3. As a next step, increase the temperature from 80⁰ C to 130-135⁰ C
4. The bath should be run at the same temperature for 30-60 minutes.
5. To neutralize the pH of the bath, lower the temperature down to 80-90⁰ degrees Celsius over a period of 10-20 minutes using alkalis.
6. As a final step, add the reactive dyes and salt to the dye bath according to the recipe, and let it run for 20-30 minutes.
7. As soon as the temperature is lowered to 60⁰ C, the alkalis (Soda Ash ) should be added and the dye will be run for 30-60 minutes for the cotton parts to be dyed.
8. Drop the dyebath and proceed with the after-treatment process after dropping the dyebath.

After treatment process

In order to improve colorfastness, it is very important to wash and clean properly in order to remove all dyes that are not yet fixed to the fabric. After polyester dyeing, the unfixed disperse dyes are removed by alkalis due to their action on the unfixed dyes. As a final step, the after treatment process is carried out as described in the recipe below.

Chemical name	Amount
Detergent	3 gm/L
Caustic	3 gm/L
Time	15-30 min
Temperature	70-800

1. Rinse twice with hot and cold water successively.
2. Then treat the fabric with mentioned above recipe
3. Rinse hot and cold wash successively.
4. Then dyer the sample.
5. Finally check the shade.

Final Result

Here is the final result of our sample